Engineering a Mn Polarization Center in Bi19S27Cl3 for Efficient Ammonia Production under Near-Infrared Light

Abstract

As an elegant strategy that concurrently mitigates water pollution and synthesizes a crucial chemical feedstock, photocatalytic nitrate reduction to ammonia (PcNRA) emerges as a promising green technology, paving the way for carbon-free ammonia production. This study reports the pioneering application of the narrow-bandgap semiconductor Bi19S27Cl3 (BSC) with Mn polarization centers for PcNRA. Due to the Jahn−Teller effect and incoordinate electron spin, the doped Mn induce local structural distortion and electronic restructuring to form polarized active sites. These sites contribute synergistically by narrowing the bandgap for broader solar absorption, facilitating the separation and transport of photogenerated charges, and generating localized heat under illumination to accelerate reaction kinetics. The optimized 5-Mn-BSC catalyst achieves a remarkable photocatalytic NH3 production rate of 138.6 μmol·g-1·h-1 from NO3- reduction under NIR irradiation and 2150.2 μmol g-1 h-1 from NO2- reduction under UV-vis light irradiation. This work provides novel design principles and in-depth mechanistic understanding for advancing NIR-driven nitrogen resource conversion.